/* *  linux/mm/vmalloc.c * *  Copyright (C) 1993  Linus Torvalds */#include <asm/system.h>#include <linux/config.h>#include <linux/signal.h>#include <linux/sched.h>#include <linux/head.h>#include <linux/kernel.h>#include <linux/errno.h>#include <linux/types.h>#include <linux/malloc.h>#include <asm/segment.h>struct vm_struct {	unsigned long flags;	void * addr;	unsigned long size;	struct vm_struct * next;};static struct vm_struct * vmlist = NULL;/* Just any arbitrary offset to the start of the vmalloc VM area: the * current 8MB value just means that there will be a 8MB "hole" after the * physical memory until the kernel virtual memory starts.  That means that * any out-of-bounds memory accesses will hopefully be caught. * The vmalloc() routines leaves a hole of 4kB between each vmalloced * area for the same reason. ;) */#define VMALLOC_OFFSET	(8*1024*1024)static inline void set_pgdir(unsigned long dindex, unsigned long value){	struct task_struct * p;	p = &init_task;	do {		((unsigned long *) p->tss.cr3)[dindex] = value;		p = p->next_task;	} while (p != &init_task);}static int free_area_pages(unsigned long dindex, unsigned long index, unsigned long nr){	unsigned long page, *pte;	if (!(PAGE_PRESENT & (page = swapper_pg_dir[dindex])))		return 0;	page &= PAGE_MASK;	pte = index + (unsigned long *) page;	do {		unsigned long pg = *pte;		*pte = 0;		if (pg & PAGE_PRESENT)			free_page(pg);		pte++;	} while (--nr);	pte = (unsigned long *) page;	for (nr = 0 ; nr < 1024 ; nr++, pte++)		if (*pte)			return 0;	set_pgdir(dindex,0);	mem_map[MAP_NR(page)] = 1;	free_page(page);	invalidate();	return 0;}static int alloc_area_pages(unsigned long dindex, unsigned long index, unsigned long nr){	unsigned long page, *pte;	page = swapper_pg_dir[dindex];	if (!page) {		page = get_free_page(GFP_KERNEL);		if (!page)			return -ENOMEM;		if (swapper_pg_dir[dindex]) {			free_page(page);			page = swapper_pg_dir[dindex];		} else {			mem_map[MAP_NR(page)] = MAP_PAGE_RESERVED;			set_pgdir(dindex, page | PAGE_SHARED);		}	}	page &= PAGE_MASK;	pte = index + (unsigned long *) page;	*pte = PAGE_SHARED;		/* remove a race with vfree() */	do {		unsigned long pg = get_free_page(GFP_KERNEL);		if (!pg)			return -ENOMEM;		*pte = pg | PAGE_SHARED;		pte++;	} while (--nr);	invalidate();	return 0;}static int do_area(void * addr, unsigned long size,	int (*area_fn)(unsigned long,unsigned long,unsigned long)){	unsigned long nr, dindex, index;	nr = size >> PAGE_SHIFT;	dindex = (TASK_SIZE + (unsigned long) addr) >> 22;	index = (((unsigned long) addr) >> PAGE_SHIFT) & (PTRS_PER_PAGE-1);	while (nr > 0) {		unsigned long i = PTRS_PER_PAGE - index;		if (i > nr)			i = nr;		nr -= i;		if (area_fn(dindex, index, i))			return -1;		index = 0;		dindex++;	}	return 0;}void vfree(void * addr){	struct vm_struct **p, *tmp;	if (!addr)		return;	if ((PAGE_SIZE-1) & (unsigned long) addr) {		printk("Trying to vfree() bad address (%p)\n", addr);		return;	}	for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {		if (tmp->addr == addr) {			*p = tmp->next;			do_area(tmp->addr, tmp->size, free_area_pages);			kfree(tmp);			return;		}	}	printk("Trying to vfree() nonexistent vm area (%p)\n", addr);}void * vmalloc(unsigned long size){	void * addr;	struct vm_struct **p, *tmp, *area;	size = PAGE_ALIGN(size);	if (!size || size > high_memory)		return NULL;	area = (struct vm_struct *) kmalloc(sizeof(*area), GFP_KERNEL);	if (!area)		return NULL;	addr = (void *) ((high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1));	area->size = size + PAGE_SIZE;	area->next = NULL;	for (p = &vmlist; (tmp = *p) ; p = &tmp->next) {		if (size + (unsigned long) addr < (unsigned long) tmp->addr)			break;		addr = (void *) (tmp->size + (unsigned long) tmp->addr);	}	area->addr = addr;	area->next = *p;	*p = area;	if (do_area(addr, size, alloc_area_pages)) {		vfree(addr);		return NULL;	}	return addr;}int vread(char *buf, char *addr, int count){	struct vm_struct **p, *tmp;	char *vaddr, *buf_start = buf;	int n;	for (p = &vmlist; (tmp = *p) ; p = &tmp->next) {		vaddr = (char *) tmp->addr;		while (addr < vaddr) {			if (count == 0)				goto finished;			put_fs_byte('\0', buf++), addr++, count--;		}		n = tmp->size - PAGE_SIZE;		if (addr > vaddr)			n -= addr - vaddr;		while (--n >= 0) {			if (count == 0)				goto finished;			put_fs_byte(*addr++, buf++), count--;		}	}finished:	return buf - buf_start;}